Two environmental groups wanted Duke Energy to also build a solar farm that would rival the largest solar projects in the country.

A state utility board gave approval to Duke Energy to build a natural gas plant at the energy giant's current coal-burning plant in Anderson County, but denied a request from two environmental groups that wanted Duke Energy to also build a solar farm that would rival the largest solar projects in the country.

Duke will make a final decision later this spring whether it will build the natural gas plant, said Duke Energy spokesman Ryan Mosier.

The project would be a "significant investment" by Duke Energy and would mean up to 500 jobs during its construction, Mosier said.

The Public Service Commission, which regulates the state's utilities, directed Duke Energy to "continue to consider cost-effective solar generation as a part of its planning for its future generation mix" but denied a request from the Coastal Conservation League and the Southern Alliance for Clean Energy to add a contingency to the approval that would force Duke to take bids from contractors to build 375 megawatts of solar energy to accompany the natural gas plant.

Duke plans to shutter two coal-burning units at its W.S. Lee Steam Station this year and begin converting a third unit next year into a 750 megawatt natural gas burning generator, the company has said.

The commission decided that Duke doesn't need the additional 375 megawatts of capacity right now and could put in its own solar proposal at any time.

Duke has said it is studying potential projects and wants to add solar to its portfolio in South Carolina, but hasn't announced any projects yet.

Representatives of the pro-solar groups couldn't be reached for comment late Thursday afternoon.

The company has announced its support of a comprehensive solar bill that's waiting for debate in the Senate that would add structure to future solar efforts in the state.

"Duke Energy supports and encourages the use of cost-effective solar energy in ways that enhance the environment and preserve the reliability of the electric system," Mosier said.

"By passing this bill, South Carolina has a real opportunity to create a solar strategy that is cost-effective, gives customers' choices, reduces the reliance on traditional energy sources, maintains electric reliability and a dependable grid, grows the economy and is fair to everyone."

The two groups asked the commission to delay the opening of the natural gas facility until 2018 because they said customers didn't need the energy until then. The commission left the decision on the plant's in-service date up to Duke to decide based on electrical demand and costs.

If Duke decides to build the natural gas plant, it would satisfy "significant" customer needs it expects to see in the next 15 years, Mosier said.

"Duke Energy's commitment is to meet our customers' needs in a way that balances affordable, reliable and increasingly clean electricity," he said.